US Avenger an 'important boost' for Ukrainian air defense, top commander says

U.S. Avenger air defense systems, which are mounted on Humvees and are highly mobile, are now being used to protect major Ukrainian cities and to protect Ukraine's ground forces near the frontline, according to a senior Ukrainian official.

One of Ukraine's most senior commanders also confirmed to ABC News that all 12 Avenger systems promised by the Biden administration are in Ukraine and operational. In November, four short-range Avenger air defense systems were announced as part of a $400 million defense package for Ukraine.

Lt. Gen. Serhiy Nayev, who is in charge of Ukrainian forces stationed along the border with Belarus and Russia, described the Avenger as "a very important boost" for Ukraine's air defenses in an exclusive interview.

The Avenger has laser and infrared technology to identify and track targets and its dual launchers can carry a total of eight heat-seeking Stinger missiles.

ABC News was the first media organization to film an Avenger in a secret location in central Ukraine.

Nayev said the air defense system had already proved to be "very effective" because when deployed they are "constantly on the move" and "ready for the next strike".

The Avenger can be used to intercept helicopters or low-flying aircraft.

However, Nayev said the technology was proving adept at intercepting cruise missiles and lethal attack drones at night, or in the day and in any type of weather.

"It's good for the troops [operating the system,] as they feel confident they can hit the target," he said.

Ukraine's air defenses are again in sharp focus after a barrage of Russian ballistic and cruise missiles struck Kyiv on Monday night, including several hypersonic "Kinzhal" missiles.

Moscow previously claimed the Kinzhal, which means "dagger" in Russian, could not be shot down.

Ukrainian officials claimed all 25 missiles fired on Monday night were shot down.

However, one of the explosions did cause minor damage to a component of a highly sophisticated Patriot air defense battery, according to a Ukrainian military source and a U.S. official.

The U.S. official said the overall Patriot system was still operational and could be fixed "soon."

Ukrainian officials said their ability to defend Kyiv against an "exceptional" barrage of Russian missiles showed how much their overall defenses had improved.

Nayev told ABC News that the efficiency of Ukraine's air defenses had "increased by 100%" thanks to donated systems from Europe and the U.S.

As well as one highly sophisticated Patriot system and the 12 Avengers, the Biden administration has pledged to supply Ukraine with eight advanced Surface-to-Air NASAMS systems, a Hawk air defense system and other types of radar missiles and guns for air defense.

Ukraine's European allies have also supplied an array of advanced air defense systems such as Germany's sophisticated IRIS-T as well as the long-range Italian and French made SAMP/T.

For Vitaliy, a commander in Ukraine's Air Force whose unit operates an Avenger system, the technology is a massive leap from old Soviet systems which Ukraine relied on in the past.

Vitaliy, who didn't give his surname for security reasons, and his team recently completed training by American military personnel on the Avenger system in Germany.

With his family based in Kyiv, he thanked the United States for helping Ukraine to protect its skies and the people he loves.

"I only have my family, and I must protect them," he said.

ABC News' Luis Martinez contributed to this report.